Motivation is fickle. One week you’re amped up to crush your fitness goals, and the next week you’ve got every excuse in the book to avoid the gym. Of course, there are tricks to help you stick with a workout program, such as goal setting and finding an accountability partner. But if what you really lack is motivation, it may be time to blame your brain. Dopamine, the neurotransmitter linked to happiness and rewards, also appears to play a role in the motivation to move. So if you can’t seem to get off your ass and out the door, the cause may go deeper than a simple dislike of exercise.

Given its headline-grabbing role in the science of addiction and love, dopamine has a sexier reputation than most brain chemicals. “Dopamine may be the most popular neurotransmitter due to its role in motivation, and, of course, happiness,” says Dr. Michele Leno, a licensed psychologist and the founder of DML Psychological Services.

“You release dopamine when you engage in pleasurable activities,” Leno says. But you don’t just release this feel-good chemical whileyou’re having a good time. You release it in anticipationof pleasure. For instance, if you love pizza, your body releases dopamine not just when you eat pizza, but when you smell it, see it, or walk by your favorite pizza place. Dopamine is like the drug before the drug — the anticipation of the positive experience to come.

In this respect, dopamine is responsible for spurring action to achieve a goal, according to a 2013 study published in Neuron. So if you’re sitting on the couch waiting for a lightning strike of motivation to hit you before you head to the gym, a lack of dopamine could be holding you back.

Use Dopamine to Motivate Your Workout

If dopamine is released primarily in response to the anticipation of pleasure, it’s pretty safe to assume that people who hate exercise are fighting an uphill battle. Unfortunately, that battle appears to become more challenging if you’re out of shape. A 2016 article published in Cell Metabolism found that obese mice were more physically inactive than their lean peers, but not because they were heavier. The mice in the study that ate a high-calorie diet became physically inactive beforethey put on substantial weight, and their decreased activity was linked primarily to a change in dopamine receptors in the brain.

But here’s the catch: Exercise itself increases the release of dopamine. So where exercise is concerned, you may need to put the proverbial cart before the horse and start your workout habit beforeyour motivation kicks in. People who exercise regularly know how good they’ll feel post-workout, so that dopamine is already firing in their brains. To get to that point, you’ll need to start and finish a workout before enjoying its feel-good effects.

However, you don’t need to go whole hog on some vomit-inducing CrossFit session to start feeling more motivated. You can build up with lower-intensity exercise until your workout habit is solidified. “If being a fiercely competitive athlete isn’t your thing, walking, yoga, or other low-impact exercises can increase dopamine levels associated with improved mood and sense of well-being,” says Dana Ryan, Ph.D., and senior manager, Sports Performance and Education at Herbalife Nutrition.

Think of it this way: What do you actually like to do that’s active? When was the last time you felt a good high from exercise? You don’t need to do that thing religiously — you just need something to kick off the first wave of exercise-related happiness to get yourself motivated for next time.

Try seeking out workouts you might actually look forward to. Maybe it’s time to schedule a regular pick-up game of basketball with your friends, or to plan a weekend hiking trip. If, as a kid, you loved riding your bike, why not invest in a new set of wheels and sign up for a cycling event? Then, after each workout, make a point of noting how accomplished and successful you feel. By choosing to engage in exercise even without the action-spurring pre-workout dopamine boost, you’re developing the habits that ultimately help set this brain chemical in motion.